The primary objective of the BEST trial is to determine whether the addition of betablockers to standard therapy reduces the total mortality of patients with moderate to severe chronic congestive heart failure. The secondary objective us to evaluate the effects of beta-adrenergic blockade on: (a) cardiovascular mortality total due to worsening heart failure due to sudden death (b) quality of life (c) hospitalizations and costs (d) left ventricular ejection fraction at 3 and 12 months of therapy (e) the incidence of myocardial infraction (f) combined transplant/mortality endpoint (g) changes in the need for co-therapy. In addition, it is planned to assess the impact of etiology, race, ejection fraction and gender on the effect of treatment on primary and secondary outcomes.